Examination of the expression of various appendage-patterning genes in butterfly wings have shown that a few are expressed in patterns suggestive of roles in wing color pattern formation. For example, Distalless (Dll) gene expression has been found in cells destined to become the focus of the eyespot color pattern in both species of butterflies examined thus far, Precis coenia and Bicyclus anynana. One of the goals described in this proposal is to determine if the patterning gene Dll functions in eyespot formation. This will be accomplished by characterizing the effect of ectopic expression of the gene encoding Dll on eyespot formation and inhibiting the expression of Dll within the developing eyespot. Other genes involved in eyespot determination and formation will be identified using a PCR-based screen for genes expressed preferentially in the eyespot. The function of these genes will be tested using methodologies developed for testing the function of the Dll gene and in some cases, by implanting the gene product directly. These studies may reveal that the developmental pathways used to form butterfly wing patterns utilize the same mechanisms and genes used in determining body and appendage patterns in insects and vertebrates. Thus, given the tremendous variety of butterfly wing patterns, studying their development would provide a deeper understanding of the mechanisms guiding intricate cellular pattern development in other animals.